1. Field of the Invention
This invention relates generally to the field of orthodontic appliances. More specifically, the present invention relates to a process for designing and manufacturing orthodontic aligners for use in orthodontic treatment in which individual teeth are urged along predetermined paths so as to cause realignment thereof.
2. Description of the Related Art
Dentistry is currently involved in a process of rapid change in what has until recently been considered conventional practice. Such changes are taking place in many fields and are often the result of the integration of new computer-based digital technologies, which tend to become the core of powerful new methodologies. In the dental specialty of orthodontics, for example, the process of laser scanning and three-dimensional imaging of a patient's teeth and then the manipulation of the virtual tooth positions within a computer-aided-design (CAD) environment utilize these new technologies. Orthodontists and some dentists routinely use three-dimensional imaging and CAD manipulation of tooth positions and tooth relationships as part of an approach to straightening teeth.
To use the digital services, an impression of a patient's teeth, gums, and soft tissue is taken. From the impression, a positive stone model is poured and allowed to cure. Instead of retaining a patient's models for in-office case diagnosis and treatment planning as in the past, the attending orthodontist will instead ship the patient's models to a regional commercial orthodontic service center. A number of services are available to a doctor using such service centers, and these services will be provided according to a prescription and other instructions sent along with the patient's models to the service center.
U.S. Pat. No. 5,139,419 (Andreiko) discloses a methodology beginning with scanning of a patient's models as described above to produce a digital code that can be assimilated by computer software. For this step, models can be scanned by any of several current methods to create digital code representing a virtual model of the teeth above the gum line, gums, and soft tissues that can be visually displayed on a computer screen. Andreiko describe methods for the virtual separation of individual teeth from adjacent teeth and soft tissues, and methods for bodily repositioning of individual teeth and groups of teeth.
FIG. 1 is an occlusal view of a dental malocclusion. As shown, teeth 2 are not properly aligned. The dental malocclusions shown in FIG. 1 are typically corrected with a series of orthodontic aligners. The orthodontic aligners are typically manufactured based on dental casts that are optically scanned as discussed above. One or more orthodontic aligners are user during the treatment to realign the teeth.
FIG. 2 depicts a set of teeth that have undergone treatment using the optically scanned dental casts. The aligned teeth have a spacing D. This space between the teeth is based in part on using data regarding the teeth above the gum line, without considering the roots of the teeth.